This invention relates to a method of manufacturing a composite sliding material which is usable for the sliding portion of or the rotating portion of various industrial machines and automobile etc.
A method of producing a bimetal strip (hereinunder referred to as a composite sliding material) which is necessary for making a plain bearing or the like for automobiles is disclosed in Japanese Patent Publication No. 27197/1973 (as a prior art for producing a composite sliding material to be employed in such a usage). This literature shows a method of producing a composite sliding material which method comprises the steps of casting or inserting a billet for the sliding portion, which is formed of alloy of aluminum and tin, into a sleeve type protecting material which is formed of pure aluminum and thereafter extruding both simultaneously, as well as a method of producing a composite sliding material wherein a steel material is pressure-bonded to the protecting material of the composite sliding material which in this case serves as an adhesive.
The conventional methods of producing a composite sliding material including the above-described methods have the following defects:
The composite sliding material which has been extruded is entirely enveloped by a protecting material of pure aluminum and in order to form this sliding material to a finished composite sliding material product, the step of cutting the aluminum protecting material is necessary for the purpose of exposing the sliding portion covered by the protecting material. This fact leads to an increase in manufacturing costs. Furthermore, in the case of producing the composite sliding material by extruding a plane billet base material and a plane protecting material which are merely arranged in parallel and in contact with each other, the sliding material obtained by the extrusion is apt to crack at the end portions along the interface.